The 'walking 10k' is the wellness trend of walking 10,000 steps a day — popularised by smartwatch goals and TikTok. Some users prefer walking 10 kilometres or 10,000 steps as a daily routine, often filming themselves doing it. If your teen is into it, they are taking up a healthy, low-intensity habit. The 10,000-step target itself is an arbitrary marketing figure from 1960s Japan rather than a medical recommendation, but walking that much is genuinely beneficial.